Circuit for transmitting binary data on the electric network using several transmission channels

Abstract

The present invention relates to a circuit for transmitting binary data on an electric network. The circuit includes a modulator, a demodulator and a digital circuit for controlling the modem and interpreting binary data. The circuit further includes a circuit for allocating a transmission channel to a communication and means for selecting, among several channels, an idle channel.

What is claimed is: 
     
       1. A circuit for communicating binary data on an electric network comprising: a first modem having a modulator, and a demodulator;   a digital circuit for controlling the first modem and interpreting the binary data; and   an allocation circuit, coupled to the first modem and the digital circuit, for allocating a transmission channel to a communication, the allocation circuit including means for selecting, from a plurality of transmission channels, an idle transmission channel;   wherein the allocation circuit includes a selection device that selects the transmission channel to allocate based upon the transmission channel having a best transmission level from a plurality of idle transmission channels, selection being performed when the first modem operates as a receiver modem during a frame for establishing a communication sent on the plurality of idle transmission channels by a transmitter modem, the selection device supplying the digital circuit with a signal indicating the transmission channel.   
     
     
       2. The circuit of claim 1, wherein: the selection device controls a modulation device that modulates, on at least one frequency selected from a plurality of frequencies which define the plurality of transmission channels, a first signal already modulated by the modulator of the first modem; and   the selection device controls a demodulation device that demodulates a second signal that is received on the transmission channel.   
     
     
       3. The circuit of claim 1, wherein the frame for establishing the communication includes a first sequence containing a duration of a message that is to be sent by the transmitter modem. 
     
     
       4. The circuit of claim 3, wherein the frame for establishing the communication further includes a second sequence containing respective addresses of the transmitter modem and of at least one modem to which the frame is addressed. 
     
     
       5. The circuit of claim 4, wherein the circuit, upon receiving the frame for establishing the communication which was addressed to it, transmits an answer frame to the transmitter modem, the answer frame being transmitted only on the transmission channel and having sequences similar to the frame for establishing the communication. 
     
     
       6. The circuit of claim 3, wherein the frame for establishing the communication begins with a pseudo-random sequence having a predetermined duration selected according to a duration required for selection of the transmission channel by the allocation circuit, the pseudo-random sequence being followed by a predetermined sequence enabling the digital control circuit to identify the frame as a frame for establishing a communication. 
     
     
       7. The circuit of claim 3, wherein the digital circuit supplies the allocation circuit with a configuration signal indicating which of the plurality of transmission channels are idle and which of the plurality of transmission channels are busy. 
     
     
       8. The circuit of claim 7, wherein the digital circuit assumes that an allocated transmission channel becomes idle at the end of the duration contained in the frame which has established the communication on the allocated transmission channel. 
     
     
       9. A circuit for communicating binary data between a first modem and a second modem that are coupled to an electric network, the first modem having a first modulator and a first demodulator, the circuit comprising: a first input terminal to receive a first signal based on a first communication over the electric network from the second modem;   a second input terminal to receive a second communication from the first modulator;   a first output terminal to transmit a second signal over the electric network to the second modem, the second signal being based on the second communication;   a second output terminal to transmit the first communication to the first demodulator;   an allocation circuit, coupled to the first and second input terminals and the first and second output terminals, to allocate a first transmission channel to the first communication, the first transmission channel being allocated from a plurality of transmission channels of the electric network, each transmission channel of the plurality of transmission channels being respectively defined by a respective frequency of a plurality of frequencies; and   a control circuit, coupled to the allocation circuit, to interpret the binary data and control the allocation circuit;   wherein the allocation circuit includes a selection circuit, coupled to the first input and the control circuit, to select the first transmission channel from the plurality of transmission channels, the first transmission channel being selected from at least one idle transmission channel of the plurality of transmission channels and having a highest transmission level of each at least one idle transmission channel that receives the first signal.   
     
     
       10. The circuit of claim 9, wherein the selection circuit selects the first transmission channel from each at least one idle transmission channel that receives the first signal during a frame for establishing the first communication. 
     
     
       11. The circuit of claim 10, wherein the selection circuit sends an indication signal to the control circuit indicating the first transmission channel. 
     
     
       12. The circuit of claim 10, wherein the selection circuit sends an indication signal to the control circuit indicating each at least one idle transmission channel of the plurality of transmission channels and each busy transmission channel of the plurality of transmission channels. 
     
     
       13. The circuit of claim 9, wherein the allocation circuit further includes a modulation circuit, coupled to the selection circuit, the second input terminal, and the first output terminal, to modulate the second communication on at least one respective frequency of the plurality of frequencies. 
     
     
       14. The circuit of claim 13, wherein: the selection circuit sends an indication signal to the control circuit indicating each at least one idle transmission channel of the plurality of transmission channels and each busy transmission channel of the plurality of transmission channels;   the modulation circuit modulates the second communication on each respective frequency that respectively defines each at least one idle transmission channel to generate the second signal; and   the modulation circuit transmits the second signal over the electric network.   
     
     
       15. The circuit of claim 14, wherein: the modulation circuit modulates a frame for establishing the second communication on each respective frequency that respectively defines each at least one idle transmission channel to generate a modulated frame for establishing the second communication; and   the modulation circuit transmits the modulated frame before transmitting the second signal.   
     
     
       16. The circuit of claim 15, wherein the frame for establishing the second communication includes an initial sequence having a duration that allows a second allocation circuit, coupled to the electric network and between the second modem and the electric network, to select a single idle transmission channel from each at least one idle transmission channel in common with the allocation circuit on which to receive the second signal prior to receiving the second signal. 
     
     
       17. The circuit of claim 16, wherein the duration of the initial sequence allows a plurality of allocation circuits, each coupled to the electric network and between the electric network a respective one of a plurality of modems, to select a single idle transmission channel from each at least one idle transmission channel in common with the allocation circuit on which to receive the second signal prior to receiving the second signal. 
     
     
       18. The circuit of claim 17, wherein the frame for establishing the second communication further includes a group code, following the initial sequence, indicating that at least two of the plurality of modems are to receive the second signal. 
     
     
       19. The circuit of claim 16, wherein the frame for establishing the second communication includes a sequence that identifies the frame for establishing the second communication. 
     
     
       20. The circuit of claim 16, wherein the frame for establishing the second communication includes a sequence that contains an address of the first modem and an address of the second modem when the second modem is to receive the second communication. 
     
     
       21. The circuit of claim 16, wherein the frame for establishing the second communication includes a sequence that indicates a length of the second communication. 
     
     
       22. The circuit of claim 16, wherein the frame for establishing the second communication further includes: a second sequence, following the initial sequence, that identifies the frame for establishing the second communication;   a third sequence, following the second sequence, that contains an address of the first modem and an address of the second modem when the second modem is to receive the second communication; and   a fourth sequence, following the third sequence, that indicates a length of the second communication.   
     
     
       23. The circuit of claim 13, wherein: the selection circuit sends a first indication signal to the control circuit indicating the first transmission channel;   the selection circuit sends a second indication signal to the control circuit indicating each at least one idle transmission channel of the plurality of transmission channels and each busy transmission channel of the plurality of transmission channels; and   the modulation circuit modulates the second communication on only the respective frequency that define s th e first transmission channel to generate the second signal when the second communication is responsive to the first communication.   
     
     
       24. The circuit of claim 13, wherein the allocation circuit further includes a demodulation circuit, coupled to the selection circuit, the first input terminal, and the second output terminal, to demodulate the first signal and transmit the first communication to the first demodulator. 
     
     
       25. The circuit of claim 9, wherein the allocation circuit further includes a demodulation circuit, coupled to the selection circuit, the first input terminal, and the second output terminal, to demodulate the first signal and transmit the first communication to the first demodulator. 
     
     
       26. A circuit for communicating binary data between a first modem and a second modem that are coupled to an electric network, the first modem having a first modulator and a first demodulator, the circuit comprising: a first input terminal to receive a first signal based on a first communication over the electric network from the second modem;   a second input terminal to receive a second communication from the first modulator;   a first output terminal to transmit a second signal over the electric network to the second modem, the second signal being based on the second communication;   a second output terminal to transmit the first communication to the first demodulator;   an allocation circuit, coupled to the first and second input terminals and the first and second output terminals, to allocate a first transmission channel to the first communication, the first transmission channel being allocated from a plurality of transmission channels of the electric network, each transmission channel of the plurality of transmission channels being respectively defined by a respective frequency of a plurality of frequencies; and   a control circuit, coupled to the allocation circuit, to interpret the binary data and control the allocation circuit;   wherein the first modulator is a frequency shift keying modulator and a frequengy distance between a first respective frequency of the plurality of frequencies and a second respective frequency of the plurality of frequencies is greater than a frequency distance between two frequencies of the frequency shift keying modulator.   
     
     
       27. A method of communicating between a first modem and a second modem using an electric network as a medium of transmission, the method comprising the steps of: receiving an initial portion of a communication on a plurality of transmission channels, each of the plurality of transmission channels being defined by a respective frequency of a plurality of frequencies;   allocating a first transmission channel from the plurality of transmission channels to a remaining portion of the communication; and   responding to the initial portion of the communication on the first transmission channel;   wherein the step of allocating includes a step of selecting the first transmission channel from the plurality of transmission channels according to a quality of transmission on each transmission channel of the plurality of transmission channels that receives the initial portion of the communication;   wherein the step of selecting includes steps of (A) determining an energy level of transmission on each transmission channel of the plurality of transmission channels that receives the initial portion of the communication, and   (B) choosing the first transmission channel based on the first transmission channel having a highest energy level of transmission on each transmission channel of the plurality of transmission channels that receives the initial portion of the communication;     wherein the step of selecting is performed during a frame for establishing the communication; and   wherein the method further comprises steps of filtering the communication to remove a high voltage and low frequency component of the communication; and   demodulating the communication on the respective frequency that defines the first transmission channel.     
     
     
       28. The method of claim 27,further comprising a step of transmitting the communication to the first modem responsive to the step of demodulating. 
     
     
       29. The method of clam 28, wherein the step of responding to the initial portion of the communication includes steps of: modulating a response to the initial portion of the communication on the respective frequency that defines the first transmission channel; and   transmitting the response to the initial portion of the communication over the electric network.   
     
     
       30. The method of claim 29, wherein the communication is transmitted by the second modem and received by the first modem, the response to the initial point of the communication including a second frame for establishing the communication, the second frame for establishing the communication including a sequence indicative of and address of the first modem, and an address of the second modem. 
     
     
       31. The method of claim 30, wherein the second frame for establishing the communication further includes a sequence indicative of a length of the response. 
     
     
       32. A method of communicating between a first modem and a second modem using an electric network as a medium of transmission, the method comprising the steps of: receiving an initial portion of a communication on a plurality of transmission channels, each of the plurality of transmission channels being defined by a respective frequency of a plurality of frequencies;   allocating a first transmission channel from the plurality of transmission channels to portion of the communication;   responding to the initial portion of communication on the first transmission channel;   indicating each busy transmission channel of the plurality of transmission channels and each idle transmission channel of the plurality of transmission channels;   selecting, responsive to the step of indicating, a first plurality of transmission channels on which to transmit a second communication, the first plurality of transmission channels including each idle transmission channel of the plurality of transmission channels;   modulating an initial portion of the second communication on each respective frequency of the plurality of frequencies that define each idle transmission channel; and   transmitting the initial portion of the second communication over the electric network.   
     
     
       33. The method of claim 32, further comprising steps of: modulating a frame for establishing the second communication on each respective frequency of the plurality of frequencies that define each idle transmission channel; and   transmitting the frame for establishing the second communication over the electric network.   
     
     
       34. The method of claim 33, wherein the frame for establishing the second communication includes a first sequence indicative that the frame for establishing the second communication is a frame for establishing communication. 
     
     
       35. The method of claim 33, wherein the frame for establishing the second communication includes a sequence indicative of a length of the second communication. 
     
     
       36. The method of claim 33, wherein the second communication is from the first modem and the frame for establishing the second communication includes a sequence indicative of an address of the first modem and an address of the second modem when the second communication is directed to the second modem. 
     
     
       37. The method of claim 33, wherein the second communication is directed to a plurality of modems that are coupled to the electric network, and the frame for establishing the second communication includes a sequence indicative that the second communication is directed to the plurality of modems. 
     
     
       38. The method of claim 32, wherein the communication includes a frame for establishing the communication, the frame for establishing the communication having a sequence indicative of a length of the communication, and the method further comprises a step of: presuming the first transmission channel becomes idle after a time corresponding to the length of the communication.   
     
     
       39. A circuit for communicating data between a plurality of modems including a first modem, a second modem, and a third modem, each of the plurality of modems being coupled to an electric network, the circuit comprising: means, coupled to the first modem and the electric network, for simultaneously communicating with the second modem and the third modem over a plurality of transmission channels, wherein the means for simultaneously communicating includes   allocation means, coupled to the electric network and the first modem, for allocating a first transmission channel to a first communication from the second modem, and   control means, coupled to the allocation means, for interpreting data and controlling the allocation means, and wherein the allocation means includes   selection means, coupled to the electric network and the control means, for selecting the first transmission channel from the plurality of transmission channels, the first transmission channel being selected from at least one idle transmission channel of the plurality of transmission channels and having a highest transmission level of each at least one idle transmission channel that receives the first communication.   
     
     
       40. The circuit of claim 39, wherein the allocation means further includes demodulation means, coupled to the selection means and the electric network, for demodulating the first communication and transmitting a demodulated signal based on the first communication to the first modem. 
     
     
       41. The circuit of claim 40, wherein the allocation means further includes modulation means, coupled to the selection means, the control means, and the electric network, for modulating a second communication between the first modem and the third modem and transmitting the second communication on at least one second transmission channel of the plurality of transmission channels. 
     
     
       42. The circuit of claim 41, wherein the control means includes means for informing the modulation circuit of which transmission channels of the plurality of transmission channels are idle, and the at least one transmission channel includes each of the plurality of transmission channels that are idle. 
     
     
       43. The circuit of claim 41, wherein the modulation means modulates a frame for establishing the second communication and transmits the frame for establishing the second communication on the at least one second transmission channel prior to transmitting the second communication. 
     
     
       44. The circuit of claim 39, wherein the selection means selects the first transmission channel during a frame for establishing the first communication.